The Winkler Process is a well-known method of solid fuel gasification using a fluidized bed. In this process, crushed or pulverized fuel is gasified in a fluidized bed using blast steam-oxygen, or steam-air, forced draft. This one-step process works well for the gasification of lignites; but problems are encountered in the case of bituminous coals. Such problems arise because of the high content of volatile substances in bituminous coals which produce considerable amounts of tars in the gasification process. The gasification process carbonizes the tar into particles that tend to agglomerate; and this adversely affects the reliability of gas producers of this kind.
Another well-known process of gasification of coal involves a counter-flow, multiple-stage, fluidized bed. In this process, the coal is initially outgassed by uncleaned gas, and semi-coked by hot uncleaned low-calorie producer gas, which is fed to the using equipment (a boiler plant or gas turbine) following dust removal and proper cleaning. This method is sometimes referred to as the Westinghouse process prototype.
It is an object of the present invention to provide a new and improved method of and apparatus for generating combustible gases from pulverized coal, and more particularly, coal having a high ash content, which overcome or substantially ameliorates the problems of the prior art described above.